Helanthium bolivianum "quadricostatus var. xinguensis"

Helanthium bolivianum belongs to the water-plantain family and is a small marsh plant that spreads by runners; it is recorded from Bolivia, Peru, Ecuador, Brazil, Paraguay and Argentina.¹ Along river margins and in swamps it flowers and fruits on drying ground or, depending on the rainy or dry season, lives fully submersed.¹ Long placed in Echinodorus, it has belonged to Helanthium since 2007, like the other runner-forming species.¹

Forms from the species complex circulate under changing names, among them E. xinguensis or E. quadricostatus var. xinguensis.² A name database for the genus lists this variety as a heterotypic synonym of H. bolivianum.³ The form sold under this name grows fast, spreads by runners and forms grass-like lawns in the foreground or midground, also in nano aquariums; it also grows emersed.